Construction elements made of composite materials are commonly known. Particular implementations containing plastics and organic material with a fibrous structure, which form a plastic-organic composite when combined, are also known. The plastic-organic composite has particular properties which allow for using it as a building material for construction elements, particularly those exposed to variable atmospheric conditions. Because of the method of its production, this material enables to create construction elements with rather small thickness while maintaining their hardness. Unfortunately, the increased hardness leads to an inconvenience consists in increasing the brittleness of these elements, and it is also unfavourable considering the application of these construction elements, namely using them as a pavement. That is why other elements corresponding to them are used, for improving the convenience of using the pavement by application of elastic foundations.
The other mentioned inconvenience is eliminated by obtaining a special construction, which increases the strength of a hard but brittle element. It is possible to obtain special structures thanks to a conventional method for production of plastic-organic construction elements, namely by extruding them in the form of connectable profiles, optimally closed profiles, or by increasing the thickness of the solid layer of the finished extruded element. Unfortunately, extruding of profiles to a shape has an inconvenience that consists in a possibility of wrong, non-uniform head of the longitudinal narrow thin walls. And, on the other hand, increasing the thickness of the solid layer has an inconvenience which consists in a dramatic increase of specific gravity of the finished construction element. The realisations described above are basically used by all manufacturers of composite plastic-organic construction elements, and examples of products, also with overall dimensions and mass per running meter listed, are shown on the following websites: www.pro-concept.co; www.idealtaras.pl; www.ecoteac.pl.
Irrespective of the aforementioned inconveniencies, the system connecting the hard top layer with the elastic bottom layer remains a flaw. This inconvenience was eliminated thank to a structure disclosed in application No. PL401233, where the construction element in the form of a composite formed board is made of rubber aggregate combined with polyurethane resin to the form of a homogeneous rubber-polyurethane composite formed into a specified shape with a specified height. The rubber-polyurethane blend is bonded with a composite made of plastic and organic material with a fibrous structure. The bond is a permanent bond in the area of the joint, and in the other contacting area, it is preferably impermanent. The joint has a V-shape or a Y-shape or an inverted Δ-shape, constituting a material protrusion of the organic-plastic composite into the volume of the rubber-polyurethane composite, where the letter-shape base is located in the plane of contact of both composites in the contact area outside the joint.
The organic material with a fibrous structure is preferably a wood-based material and simultaneously or interchangeably a wood fibre material, and simultaneously or interchangeably a bamboo fibre material, and simultaneously or interchangeably a straw fibre material. Preferably, the rubber-polyurethane composite constitutes the bottom layer of the composite formed board. Any of the layers may have profiles at the side free after bonding, which may be aligned lengthwise and simultaneously or interchangeably crosswise, and simultaneously or interchangeably slantwise in relation to the composite formed board. The joint may be a longitudinal joint or a point joint, and the number of the joints may be multiplied.
Although so far, the solution discussed above is the best construction element in the form of a composite board, combining a hard top element with an elastic bottom/base element in its structure, however it still suffers the major inconvenience and potential safety hazard of heavy weight of the element. This is a significant disadvantage, as the mentioned construction elements in the form of a composite formed board may be manufactured in the size of a single board with length up to even 10 m without any parameter loss.